1. Field of Invention
The present invention relates to the field of tobacco, and more particularly to a use of saline aqueous solution as a hydrated humectant for tobacco stem.
2. Description of Related Arts
During tobacco treatment process, the addition of a humectant has important effects for improving resistance to processability, transportation, warehousing, and sensuous comfort and stimulation of smoking for tobaccos. According to the mechanism of humectant, physical humectants for cigarettes mainly include three types: (1) hygroscopic humectants: this type of substances has relatively high hygroscopic property, which serves to absorb and retain moisture in cigarettes. The main components include polyol (e.g., glycerol, propylene glycol, sorbitol, etc.), tobacco itself, or hydrophilic substrates (e.g., carbohydrate, protein, pectin, etc.) contained in other plants, for example, an aldose and a derivative formula thereof reported in the Chinese Patent “NOVEL HUMECTANT FOR TOBACCO” (Application No. 98113287.1), and a konjac extract reported in the Chinese Patent “KONJAC HUMECTANT AND APPLICATION THEREOF IN CIGARETTES” (Application No. CN200910061990.9). (2) Blocking humectants, whose main components are grease-like, serve to form a blocking barrier on the tobacco surface and to prevent evaporation and dissipation of internal moisture. The blocking humectants include paraffin oil, vegetable oil, and natural oil extracts, such as the wax-type humectant for tobacco reported in the Chinese Patent “WAX-TYPE HUMECTANT FOR TOBACCO AND PREPARATION METHOD THEREOF” (Application No. CN101658323), and the multicarbon fatty alcohol and the formula of multicarbon fatty acid reported in the Chinese Patent “HUMECTANT FOR TOBACCOS” (Application No. CN201010142981.5). (3) Hydrated humectants, which may have a solvation effect with water, and are mainly some metal ion types such as a magnesium salt; however, this type of hydrated salts is usually insoluble in water and is difficult to apply, and there are very few reports on this type of humectants.
Tobacco leaves are loose porous materials and have relative high potentials for absorbing and dissipating moisture. Tobacco stems are rough and rigid veins of tobacco leaves, and features porousness, porosity, as well as equilibrium moisture content significantly greater than those of tobacco leaves, thereby having higher potentials for absorbing moisture; however, this part of moisture disappears easily, and the moisture thereof dissipates at a speed higher than that of tobacco leaves, and thus actually the moistening performance is even lower.
The raw material of tobacco stems has a rich content in pectin, which is often bonded with calcium ions and the like. By adding with soluble inorganic or organic acids, or metal saline aqueous solution thereof, the calcium ions in the calcium pectate can be replaced and converted to generate hydrated calcium ions, such as calcium oxalate, mono/di-calcium phosphate, calcium citrate, calcium lactate, thereby effectively preventing the dissipation of moisture in tobacco, improving moistening performance of the tobacco stems. Currently, there are very few reports at home and abroad on a use of a hydrated humectant to improve moistening performance of cut stems.